Determination and comparison of effective moisture diffusivity of carrot (core and cortex) during hot air drying

The present study optimized the drying temperature (50–80°C) for potato slices based on color, texture, and visual observations. At an optimized temperature (60°C), a 2D axisymmetric finite element method (FEM) was developed in COMSOL Multiphysics to predict the heat and mass transfer (HMT) in a disk‐shaped potato slice. The nonisotropic shrinkage was predicted for the potato slice by the arbitrary Lagrangian–Eulerian approach. The experimental dehydration results revealed that axial shrinkage (27.44%) was 2.5 times higher than radial shrinkage (67.39%). The simulated outcomes based on FEM revealed the realistic visualization of spatial heat transfer, moisture migration, and nonisotropic slice deformation. The predicted moisture content, surface temperature, and shrinkage properties were in good agreement with the experimental results. The shrinkage behavior was further validated using artificial neural network (ANN) to simulate the slice shrinkage. Results showed that both the COMSOL and ANN approaches can precisely predict the shrinkage‐dependent HMT model. The ANN model outperformed the COMSOL determined by mean absolute error, mean square error (MSE), root MSE, and Chi‐square (χ2) values. The successful application of the presented approach for determining dehydration characteristics may have potential for quality assessment and management of different fruits and vegetables.Practical applicationsThis journal article explores the practical industrial applications of combining finite element method (FEM)‐based heat and mass transfer model and artificial neural networks (ANNs) to improve the efficiency and quality of food drying processes. FEM is employed to simulate and predict the realistic visualization of heat and mass transfer phenomena along with non‐isotropic shrinkage, while ANN serves as a data‐driven modeling tool for process control and prediction. The integration of these two technologies offers significant advantages in the food industry, including quantification of precise temperature and moisture content, as well as to monitor the drying process of various food products, reduced energy consumption, and time.

Section: Model Validationsupporting

confidence: 92%

Finite element modeling in heat and mass transfer of potato slice dehydration, nonisotropic shrinkage kinetics using arbitrary Lagrangian–Eulerian algorithm and artificial neural network

Das,

Prasad

2024

“…Some studies showed that deformation and heat and mass transfer could not be studied separately, so the mathematical and geometric models were combined to discuss the effect of deformation on heat and mass transmission. Suvarnakuta et al (2007) The simulated drying results using effective moisture diffusion coefficient considering the moisture content and shrinkage were closer to the experimental results than that using the constant diffusion coefficient (Zheng et al, 2023). The simulated results of the hot air drying of shiitake mushroom and the microwave drying of potato based on the multiphase porous media models demonstrated the effect of deformation on heat and mass transmission (Gulati et al, 2016;Zhu et al, 2021).…”

mentioning

confidence: 58%

Simulation and experimental study on the effect of deformation on heat and mass transfer in potato chips during superheated steam drying

Fu,

Zheng,

Ren

et al. 2023

Self Cite

Superheated steam drying is a drying technology with enormous potential and numerous advantages. Volume change and substantial deformation will occur on the materials to be dried during the superheated steam drying, which would affect the heat and mass transfer of the sample. However, the influence mechanism is not clear. Therefore, the nonuniform volume change of potato slices was studied, and the deformation model (DM) and the non‐DM (NDM) were constructed and verified to study the heat and mass transfer processes of the sample. The results showed that there was little difference between the measured and simulated temperatures based on DM and NDM with a maximum error of 4.22% and 5.03%, respectively, but there was obvious difference between simulated moisture contents with a maximum error of 5.76% and 12.21%, respectively. The volume in DM was in good agreement with the experimental data. Temperature distribution and moisture distribution in potato chips during superheated steam drying were nonuniform and the maximum temperature gradient and moisture gradient appeared in the early period. The moisture gradient existed in the whole drying process, and the stress caused by the moisture gradient was the main factor causing the drying deformation.Practical applicationsThis work can reveal that the volume change and substantial deformation have a significant impact on the heat and mass transfer during drying. In production practice, there are many similar phenomena. The results would be helpful to understand the heat and mass transfer mechanism, optimize quality parameters to obtain better products in potato drying industry, and expand the applied range of the superheated steam drying technology.

“…These results clearly demonstrate that increasing the temperature of the hot air significantly improves drying efficiency (Huishuang et al, 2020). Additionally, it is noteworthy that as the temperature of the hot air increases, the slope of the moisture content curve also increases, indicating a greater variation in grain drying rate with air temperature (Zhaohui et al, 2022).

δ = \frac{σ_{T}}{\overset{T}{true}} \times 100 % = \frac{\sqrt{\frac{1}{n - 1} \sum_{i = 1}^{n} {(T_{i} - \overset{true¯}{T})}^{2}}}{\overset{T}{true}} \times 100 %,

where

δ

is the temperature inhomogeneity coefficient;

σ_{T}

is the standard deviation of sampling points;

\overset{true¯}{T}

is the average temperature of sampling points;

n

is the number of sampling points;

T_{i}

is the temperature of the i th sampling point.…”

Section: Resultsmentioning

confidence: 99%

“…Figure 8 demonstrate that increasing the temperature of the hot air significantly improves drying efficiency (Huishuang et al, 2020). Additionally, it is noteworthy that as the temperature of the hot air increases, the slope of the moisture content curve also increases, indicating a greater variation in grain drying rate with air temperature (Zhaohui et al, 2022).…”

Section: Effect Of Different Hot Air Temperatures On the Drying Processmentioning

confidence: 99%

Numerical simulation of rice drying process in a deep bed under an angular air duct

Li,

Feng,

et al. 2023

The deep‐bed drying process of rice grains was investigated through numerical simulation, employing the porous medium flow field theory and the local thermal nonequilibrium method. Moisture field of rice grains described using thin‐layer equations. On this basis, the deep‐bed drying of rice grains modeled with COMSOL, and verified its plausibility. The results showed that the drying rate of rice grains was significantly accelerated when the hot air temperature was increased from 40°C to 70°C, but the inhomogeneity of rice grains temperature increased by 29.79%, 22.31%, and 17.41% for every 10°C increase. Drying grains faster with vertically arranged an angular air duct, with a 4.88% increase in drying speed in 300 min. The temperature difference between the top and the bottom of an angular air duct with a small width is smaller, about 11°C, and the heating efficiency is better at the top, by 31.28%.Practical ApplicationsGrain dryers are often used in high‐volume grain drying operations and it has been a great challenge to save the energy consumption of the drying process. It is necessary to use numerical simulation to design a reasonable structure of the heating section to improve the energy utilization efficiency of the heating section of the grain dryer. The numerical model proposed in this article can effectively simulate the spatial distribution of moisture content of rice under different structures of grain drying units, which can be used not only for the prediction of drying time but also for analyzing the optimal heating structure from it. A technical basis is provided for the design of grain dryers.